Neurologic manifestations of HIV infection show deficits in cognitive and motor functions. Central nervous system (CNS) pathology underlying these clinical events include myelin pallor, macrophage/microglial activation, profound reactive gliosis and neuronal dropout. Interestingly, a progressive neuronal loss occurs without (to any significant degree) direct neural cell infection. Our laboratory has dedicated itself towards understanding how secretory products from immune activated HIV- I-infected macrophage/microglia produce progressive viral-associated neuropathology. Our initial work uncovered a large number of macrophage secretory products (toxins) likely involved in such neuronal damage. These include, but are not limited to, eicosanoids, proinflammatory cytokines, platelet activating factor, free radicals and excitatory amino acids (including cysteine and quinolinic acid). The specific mechanism(s) responsible for neuronal loss have not as yet been identified. In this application, we will extend our works by investigating macrophage secretions and its associated neurotoxicity to: 1) utilize "state-of-the-art" electrophysiological methodologies to determine neuronal physiologic alterations following exposure to monocyte secretory products; 2) determine how pharmacological and/ or immunological manipulations of neurotoxic pathways can be prevented or reversed during HIV- I CNS infections; 3) characterize the electrophysiological basis for neuronal injury in our SCID mouse model of HIV encephalitis. In all works, the electrophysiological analyses will Include detailed patch clamp recording techniques to assess both synaptic and voltage-gated ion channels. Using this approach we intend to develop greater understanding for how secretory products from immune activated HIV- I- infected monocytes induce neuronal injury associated with progressive cognitive and motor dysfunctions seen in HIV-affected subjects.